Per-bin DFE for advanced OQAM-based multi-carrier wireless data transmission systems

Abstract

An Apparatus for non-linear per-bin adaptive equalization in orthogonal multi-carrier data transmission systems with the Nyquist sub-channel spectral shaping and T / 2 staggering of in-phase and quadrature components is disclosed. A previously introduced linear equalization embodiments are augmented by up to three, or more decision feed-back filters, to improve performance in presence of narrow-band interference (NBI) in wire-line and wire-less data transmission systems, and to enable exploitation of implicit diversity of multi-path fading channels, both with and without transmitter-end pre-coding. Adaptation properties of per-bin DFE equalization are analyzed by computer simulation for an intermediate number of constituent sub-channels. BER performance comparison between the conventional Orthogonal Frequency Division Multiplication-(OFDM) and (Orthogonal Quadrature Amplitude Modulation (OQAM)-based multi-carrier systems of similar modulation / demodulation complexity and transmission latency is provided and the potential advantage of using spectrally well shaped orthogonal sub-channels in wireless applications is demonstrated.

Description

[0001]This application is an application filed under 35 U.S.C. §111(a), claiming benefit pursuant to 35 U.S.C. §§119-120 of the filing date of the Provisional Application Ser. No. 60 / 325,227 filed on Sep. 28, 2001, pursuant to 35 U.S.C. §111(b). The Provisional Application Ser. No. 60 / 325,227 is incorporated herein by reference for all it discloses.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an apparatus for providing equalization in orthogonal multi-carrier data transmission systems, and more particularly relates to an apparatus for providing per-bin decision feedback equalization (DFE) for advanced OQAM-based multi-carrier wireless data transmission systems, as an example of a class of multi-carrier systems with spectrally shaped and over-lapped sub-channels.[0004]2. Description of Related Art[0005]Multi-carrier (MC) data transmission systems were traditionally applied as an alternative to conventional single-carrier (SC) system...

AI Technical Summary

Benefits of technology

[0022]An object of this invention is to demonstrate the practical feasibility of DFE per-bin equalization in MC formats with overlapped and shaped sub-channel spectra, as an enabling methodology for introduction of more advanced wire-line / wireless systems and their utilization as a viable alternative to conventional DMT / OFDM systems and their flavors in terms of combination with Code Division Multiplexing Access (CDMA), with the applicability of all the flavors of DFE adaptation methods in training and decision-directed modes as used in conventional single-carrier QAM systems, including appropriately adopted Tomlinson-Harashima pre-coding. Also, an optional operation mode with interpolated data symbols in receiver and / or transmitter parts.

Problems solved by technology

This in turn leads to an increased peak-to-average power ratio and a wide range of associated problems regarding power-efficient amplification.

These problems include: requiring a relatively large dynamic range for analog-to-digital (ADC) conversion; an increased system delay and memory requirements; and a more pronounced impact of multiplicative distortions (carrier offset, phase jitter and time-selective fading) in wireless applications.

The sole reliance on the guard-time interval in OFDM wireless applications proves insufficient in case of multi-path delay spreads exceeding the length of CP, and, much more importantly, the constrained sub-channel bandwidths preclude any utilization of implicit multi-path diversity.

However, because the equalization method of Hirosaki involves the re-alignment of QAM in-phase and quadrature components and consequently exhibits a strong interaction between linear distortion and carrier / sampling phase offset compensation, it is difficult to implement (see for example, B. Hirosaki, “Generalized differential coding theorem and its application,”Electronics and Communications in Japan, Vol. 67-B, No. 12, pp.

Images